The invention relates to a display device comprising two substrates, at least one of which is transparent, with
liquid crystal material between the substrates, PA1 orientation means orienting the molecules of the liquid crystal material substantially parallel to the substrates, PA1 electrodes on at least one of the substrates, PA1 polarization means, PA1 selection means for selecting at least one pixel, an electric field being applied substantially parallel to said substrates in the operating state during selection, and PA1 drive means for supplying a signal voltage to an electrode coupled to the pixel.
Display devices of this type are used in flat-panel display devices such as television, monitors, alphanumerical displays etc.
A display device of the above-mentioned type is described in EP-A-0 667 555. This device is based on the "in plane switching effect" and switches between different electro-optical states with the aid of the electric field directed substantially parallel to the substrates and is therefore referred to as "horizontal electrical field type display". However, this effect is much slower than the generally used (twisted nematic) TN effect so that it is not usable or hardly usable in applications where a high speed is required (video, monitors).
EP-A-0 667 555 describes how the switching speed can be increased, but the optimally realized switching times were between 25 msec and 30 msec, while a full transition within one field time, which is typically 16.7 msec at a signal frequency of 60 Hz, is desired for video applications.